Aspect ratio trouble

Follow the link to the gallery page to see what this image should really look like. The insidious part is that it looks fine in the preview, it's only after you hit "Post" that the problem occurs.

I took this picture with the camera rotated for portrait mode, then rotated it and performed other processing in an image editor. I left the EXIF intact when I saved it. When I uploaded to the gallery, it came up sideways so I needed to rotate it again; that's OK, I understand that feature was intended for people who upload straight from the camera. But it appears to lead to this problem. I don't have any trouble with images that weren't rotated.

I can work around the problem by saving without EXIF, but I like to have all the shot details available.